Three dimensional objects can be made rapidly and automatically by rapid prototyping and manufacturing (RP&M). RP&M has proven to be a cost effective technique used to develop prototypes and to manufacture various three dimensional products. RP&M is usually classified according to specific techniques. Each technique is discussed seriatim below.
A first known technique for making three dimensional objects is by applying successive layers of unsolidified, fluid-like material to a working surface. The layers are then selectively solidified according to cross-sectional computer data representing the object. These solidified layers, or laminae, are typically formed of a photo polymer liquid material and solidified via visible or ultraviolet electromagnetic radiation from a laser. More specifically, his technique involves applying liquid material to areas which will, and which will not, be part of the finished three dimensional object. The radiation is then used to solidify only those areas that are part of the three dimensional object. Often referred to as stereolithography, this technique is known and disclosed in several patents and patent applications, for example, U.S. Pat. No. 4,575,330 to Hull. Similarly, layers of a powered material can be selectively solidified by depositing a chemical binder material thereon.
Another type of RP&M is selective deposition modeling, which creates three dimensional objects by selectively depositing a liquid like material onto a working surface in patterns that become part of a solidified layer. That is, a layer is deposited based on cross-sectional data that represents slices of the three-dimensional object and is then solidified. A subsequent layer is added and solidified to the previously formed solidified layer. By repeating these steps, a three dimensional object is built lamina-by-lamina. With this technique, the liquid material is flowable but only deposited in the regions that form the three dimensional object.
Yet a third technique used for RP&M is laminated object manufacturing. With this method, three dimensional objects are formed by stacking sheets of material together wherein each sheet is adhered to another. The stacked sheets are then selectively cut in a particular order to form the desired three dimensional object, according to computer data representing the cross-sectional slices of the three dimensional object.
While these techniques have allowed for the manufacturing of many different types of three dimensional objects, they have not been useful in the creation of ophthalmic devices. Heretofore, the RP&M techniques described above have only achieved surface variations of the object of approximately 50 microns or greater.